Geochemical facies model of ore formation in the Grythyttan-Hällefors area, Bergslagen, Central Sweden

Abstract

With 8 figures ZusammenfassungDie verschiedenen Eisen-und Manganerz-Bildungen des Grythyttan-H~illcfors-Gebietes zeigen Verhaltnisse auf, die einem systematischen Wechsel der Bedoxbedingungen wiedergeben, yon oxidischer B~indereisenerzbildung bis hin zu stark reduzierten graphitfiihrenden Schiefem. Dieses Phanomen wird durch ein Fazies-Modell erkl~rt. Die unterschiedliehen Mflieu-Bedingungen werden auch als Ursache ffir die geochemische Diferentiation unedler Metall-Ablagerungen in Cu-Erze angesehen, die mit Mineralien assoziiert sind, die Bi, Co, Mo, As, Zn, Pb, Au fiihren und in Pb-Zn-Ag-Erze in Verbindung mit Sb-, Mn-, As-, Sn-und Cu-fiihrenden Mineralien. Die r~iumlichen Beziehungen zwischen Ablagerungen dieser zwei Gruppen und gewissen Eisen-und Mangan-Bildungen weisen auf eine gemeinsame Quelle aller Metalle bin, die m6glicherweise mit exhalativen Derivaten eines basischen Vulkanismus in Verbindung steht. AbstractThe different iron and manganese ore deposits of the Grythyttan-H~illefors area display an arrangement that reflects a systematic change in redox conditions from oxidic banded iron formation into highly reduced graphite-bearing slates. This phenomenon is explained by a facies model. The different environmental conditions are also held to be responsible for the geochemical differentiation of base metal deposits into Cu ores associated with minerals of Bi, Co, Mo, As, Zn, Pb, Au, and Pb-Zn-Ag ores associated with minerals of Sb, Mn, As, Sn, Cu. Spatial relationships between deposits of these two groups and certain iron and manganese deposits point to a common source of all metals, possibly connected with exhalative derivates from basic volcanism. R~sum6Les diff6rents gisements de minerais de Feet Mn de la r6gion de Grythyttan-H~illefors montrent une disposition qui r6fl6te un changement syst6matique dans les ernolitions de r6duction des formations ruban6es de fer oxyd6 en phyllades graphiteux. Ce ph6nom6ne s'explique suivant un mod61e faci6tal. Les diff6rentes conditions de l'environnement sont ainsi rendues responsables de la dfff6rentiation g6oehimique des gisements m6tallif6res de base en minerals de Cu associ6s ~ des min6raux de Bi, Co, Mo, As, Zn, Pb, Au et des minerals de Pb-Zn-Ag associ6s ~ des min6raux de Sb, Mn, As, Sn, Cu. Des relations spatiales entre les gisements de ces deux groupes et eertains gisements de Feet Mn indiquent une source commune pour tousles m6taux, en liaison possible avec des 6manations du volcanisme basique. I~paTx~oe co~epa~aimePas~H~ie 05pa30BaHH~I ~eJIe3HCTI~IX H ~apraH~eB~iX py~ B 05JIaCTH Grythyttan-i~llefors yEaBl~IBa~0T Ha TaKHe BBaHM00TH0~eHH~I, IIpH KOTOpI~IX tIMeJIa l~IeCT0

Some aspects of the silver mineralization in the Hällefors region (Bergslagen, Sweden)

“…Conclusions. Previous work (Zakrzewski, 1982;Oen et al, 1982) has suggested that the Ag-bearing H~illefors deposits were probably formed by the action of metamorphic solutions on sediments of volcano-sedimentary origin. Carbonates, especially the black carbonates, appear to have acted as collectors of the metal compounds.…”

Sulphur isotope compositions in the Åmmeberg Zn-Pb ore deposit, south-central Sweden: Genetic implications

“…Recently, both of these ore types have been interpreted as volcanic-exhalative formations (FRIETSCH, 1982;ZAKRZEWSKI, 1982). However, MAGNUSSON (1970) The geological field observations in the Ammeberg ore zone have been documented in detail by HENRIQUES (1964) andHEDSTROM et al (1989).…”

Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden

“…The Bergslagen metallogenic province has more than 2000 iron and more than 200 base metal (predominantly of the Ag Pb-Zn + Cu type) deposits and is a producer of Mn, Co, W, Mo, Au, Bi, Ce, Hg, and Se. The H/illefors silver deposit could be considered as an original volcanogenic-exhalative iron ore deposit, in the sense proposed by Large (1977) and by Zakrzewski (1982). It is presumed to have contained dispersed amounts of Ag-Pb-Zn-(+ Cu); subsequently, secondary mobilization of metals occurred due to an increase in temperature and to a lesser extent pressure, followed by the precipitation of sulphides and sulphosalts with decreasing temperature and changes of sulphur and oxygen activities.…”

“…These considerations confirm the author's conclusions in previous studies (Jasiflski, 1983) Conclusions. Zakrzewski (1982) proposed a geochemical facies model to account for the distribution of different ore types at H/illefors relative to their position in the stratigraphy with oxidesilicate-carbonate and sulphide facies corresponding to levels in a Na-leptite-K-leptite-sediment sequence. He also proposed that all the ores had a common mafic volcanogenic origin.…”